Device for intermittently supplying measured weft yarn lengths to the weft inserting device of a shuttleless weaving machine

ABSTRACT

A rotatably mounted measuring roller is adapted to receive a plurality of windings of yarn drawn from a yarn package, and an electric motor of the quick response type has a driving connection with the measuring roller. A control circuit is connected to supply current to drive the motor and is intermittently energized to drive the motor during each weftinsertion period of the weaving machine. A yarn brake is arranged to brake the yarn on the entrance side of the roller, and a continuously energized tensioning injector is arranged to exert tension on the leading end of the yarn tangentially of the roller, and in cooperation with the brake maintains the windings of yarn in constant frictional engagement with the roller.

[ Dec. 10, 1974 United States Patent [1 1 Van Duynh'oven et a1.

1 1 DEVICE FOR INTERMITTENTLY 3,675,687 7/1972 Vermeulen et 139/127 3,734143 5/1973 Svaty 139/127 SUPPLYING MEASURED WEFT YARN LENGTl-IS To THE WEFT INSERTING DEVICE OF A SHUTTLELESS WEAVING Primary Examinerl-lenry S. Jaudon MAHINE Attorney, Agent, or F irm-Marshall & Yesting Inventors: Adrianus l-lenricus Van Duynhoven,

' Deurne; Gerardus Hendrikus Kaalverink, Asten, both of Netherlands Assignee: Riiti-te Strake B.V., Deurne,

ABSTRACT Netherlands June 28, 1973 yarn package, and an electric motor of the quick re- [22] Filed:

sponse type has adriving connection with the measur- [211 App}. No: 374,376 ing ro11er. A control circuit is connected to supplycurrent to drive the motor and 1s intermittently energized to drive the motor during each weft-insertion period of the weaving machine. A yarn brake is arranged to [30] Foreign Application Priority Data June 30,1972 Netherlands..............-......

.720978 brake the yarn on the entrance side of the roller, and

a continuously energized tensioning injector is ar- References Cited UNITED STATES PATENTS 4 Claims, 2 Drawing Figures 3,670,976 Vischiani 242/4112 PATENIEL DEC 1 01974 FIG.1

FIG.2

II VQ DEVICE FOR INTERMI'I'IENTLY SUPPLYING MEASURED WEFT YARN LENGTI-IS TO THE WEFT INSERTING DEVICE OF A SI-IUTTLELESS WEAVING MACHINE BACKGROUND OF THE INVENTION The invention relates to a device for intermittently supplying measured weft yarn lengths from a stationary yarn package to the weft inserting device of a shuttleless weaving machine, comprising a measuring roller adapted to receive a number of windings of the yarn taken from the yarn package, said roller being mounted between the yarn package and the weft inserting device and driven by an electromotor, means being provided for effecting frictional contact between the measuring roller and the yarn windings encircling it, which means comprise a yarn brake provided at the entrance side of the measuring roller.

In a well-known device of this type the measuring roller is continuously driven by the electromotor during normal operation and is of a special construction, wherein an air cushion is maintained between the roller surface and the thread windings surrounding it, such that the continuously rotating roller tends to move with its circumferential surface slipping relative to the thread windings which are retained under the influence of the yarn brake. Only during part of a complete weaving cycle, i.e., only during the weft inserting phase, the thread windings are drawn through the air cushion into frictional contact with the circumferential surface of the encircled roller, as a result of the pull exerted by the weft inserting device in this case a gripper at the start of its inserting action on the yarn. After the driving contact between the weft yarn and the continuously rotating roller has been established in this manner the required weft yarn length is drawn by the measuring roller through the yarn brake from the yarn package and supplied to the weft inserting device. The drawingoff of the yarn and thereby the yarn supply to the weft inserting device is interrupted as soon as the pulling force in the thread is no longer maintained, i.e., at the end of the weft inserting phase. Then the air cushion re-establishes as a slip layerbetween the yarn and the roller. In this connection a controlled yarn brake, mounted at the delivery side of the roller between this roller and the weft inserting device plays an important role. It is controlled such that the braking action is cancelled when the weft inserting device becomes effective and is reinstituted at the end of the weft inserting phase. Reinstituting the braking action at the end of the weft inserting phase means that the tension in the yarn windings around the measuring roller is cancelled and that the thread supply is interrupted as a consequence of the roller continuing rotate only in a slipping relationship relative to the yarn windings. Reinstitution of the braking action also provides the clamping action on the thread required to permit the inserted thread length to be drawn and kept taut during the beating-up movement of the reed.

As compared with other known systems in which the weft inserting device has to accelerate a relatively large mass of yarn delivered either directly or through an intermediate storing device from the yarn package, a device of the type above mentioned has the advantage that the weft inserting device has to overcome less mass inertia, whereby a condition for a more quickly operating weaving machine appears to be fulfilled. A disadvantage of this known device particularly with quickly operating weaving machines is that the air cushion as a slip layer, as well as the controlled" yarn brake which by its nature reacts relatively slowly (i.e., in periods of several hundredths of a second) are factors limiting the velocity and also limiting the accuracy of the measuring of the yarn. Further the air consumption and the energy consumption connected with the continuous forming of the air cushion are considerable.

SUMMARY OF THE INVENTION The invention aims at removing or at least minimizing the drawbacks of the known device initially described. This is achieved in a simple and effective manner by making use of an electromotor of the quick response type, connected in a control circuit, which is intermittently energized in correspondence with the weft insertion frequency, the means for effecting the frictional contact between the yarn and the measuring roller comprising at the delivery side of the roller a continuously energized tensioning injector.

By an electromotor of the quick response type is meant an electromotor which may arrive at its full R.P.M. or may .be stopped respectively within one thousandth or a few thousandths of a second. Such electromotors, which have a disc-shaped or bell-shaped armature, are generally used in data processing apparatus.

This response time is very short in relation to a weft period of, e.g., 7O thousandths of a second and enables the required yarn length each time to be measured very accurately. As a consequence the weaving can be very economical.

In the device according to the invention the controlled yarn brake of the known device has become superfluous, since now the measuring roller acts as a brake and as a thread clamp. Thereby at the same time the factor of inaccuracy and the velocity limiting factor, connected with such yarn brake, have been cancelled.

The device according to the invention particularly offers great advantages when applied to a weaving machine in which the weft insertion is effected by means of a flowing fluid, e.g., air, and wherein the weftinserting device therefore comprises an (air) blowing nozzle. Up till now the blowing nozzle of such a weaving machine had to have relatively large dimensions in order to be able to pass the'large quantities of intermittently supplied pressurized air, which were required to generate the acceleration forces to be imparted to the thread lengths to be inserted into the shed. It often occurred thereby that the leading ends of the weft threads were blown into an incompact state. With the application of the device according to the invention, however, the acceleration forces to be imparted to the weft threads are generated essentially by the driven measuring roller, as a result of which the weft blowing nozzle may have much smaller dimensions. This means a considerable decrease in the air consumption, while the weft threads, especially the lightly twisted yarns, are much more spared. A smaller dimensioned weft blowing nozzle further has the advantage that the position of the weft thread at the entrance of the weaving shed will vary within a more narrowly delimited area, which furthers the transport of the wefts through the shed.

The air consumption of the weft blowing nozzle has been decreased even so far that there would be no objections to feeding it continuously. Thus the air supply BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the device according to the invention and of part of the weaving shed of a weaving machine, and

FIG. 2 is the electrical control diagram of that device.

In the drawing an electromotor 1 of the quick response type, e.g., a bell-shaped or disc-shaped annature motor, is mounted to one side of a motor support 2 secured to the frame 3 of a weaving machine.

On the motor shaft 4 extending at the other side of the motor support 2 a measuring disc 5 is mounted, which is preferably made of a light metal, e.g., aluminum.

The motor support 2 also supports the weft inserting device 6 which is constituted by a conventional blowing nozzle which is continuously supplied with air from a source of compressed air through a conduit schematically indicated at 7. The weft blowing nozzle 6 has a tubular discharge portion 6a facing the opening of the weaving shed 13 delimited by the upper and lower warp threads 10 and 11 respectively and by the retracted reed 12. The weft blowing nozzle 6 is horizontally positioned with the axis of its tubular inlet portion 6b tangential to the disc 5.

A conventional pneumatic yarn brake 8, likewise carried by the motor support 2, is continuously supplied with air from a source of compressed air through the schematically indicated conduit 9. Preferably this yarn brake is a conventional combined yarn-take-off and braking injector. When the yarn is to be initially threaded pressure on the actuation button 8c will cause the supplied air to be diverted so that it is discharged to the left through the tubular end portion 8b of the yarn brake, as a result of which suction is generated in the tubular end portion 8a, by means of which the leading end of the weft yarn in the supply package 14 may be threaded through the yarn brake 8. Upon release of the actuation button 8c the supplied air will flow out through the end portion 8a and thereby exert a pulling force directed to the right on the threaded weft yarn.

The weft yarn w extending from the left. end portion 8b of the yarn brake 8 in tangential relationship to the measuring disc 5 is wound a couple of times around the circumferential surface of this disc and then extends through the weft inserting nozzle 6.

It is assumed that in this embodiment the yarn brake the leading end of the weft yarn w is just in front of the discharge end of the weft blowing nozzle 6 (viz. in the location at which a previously inserted weft was cut from the weft yarn supply by a cutting device not shown in the drawing), a next weft length being about to be taken through the weaving shed which in the meantime has been changed. The signal electrical for this next weft insertion is given, e.g., by a weft detection device positioned at the other end (not shown in the drawing) of the weaving shed, which weft detection device, by detecting that the leading end of a weft has appeared at such other end of shed, indicates that a weft has been successfully inserted through the shed. The electrical signal generated by the weft detection device is a conventional way of indicating that the weaving machine is operating properly and that it is safe to introduce the next weft into the shed.

With reference to the circuit diagram of FIG. 2 it will now be explained how the motor 1 responds to such electrical signal or starting pulse generated by the weft detection device.

In the diagram of FIG. 2, I6 is a flip-flop which is set, upon, receiving the starting pulse at its setting input l7. Thereby the power amplifier 19 is activated through the OR-gate 18 and energizes the motor 1. The high voltage supplied thereby causes the motor I to speed up quickly. The tachogenerator 20, mechanically coupled to the motor 1 produces a higher voltage as the speed of the motor increases. This opposing voltage-is fed back through the OR-gate 18 to the input of the power amplifier. Thereby the energizing voltage of the motor 1 is decreased as soon as it has arrived at the desired speed. The output voltage of the tachogenerator 20 is also supplied to the integrating amplifier 21 which produces an output signal which is a measure of the number of revolutions made by the motor shaft and therefore is proportional to the; weft length conveyed by the motor. This signal is supplied to one input of a comparator 22 which at the other input receives a preset signal 23 corresponding to the desired weft length. As soon as the output signal of the integrating amplifier 21 has become equal to the preset signal 23, the comparator at its output delivers a resetting signal 24 to the reset terminal of the flip-flop 16 whereby the latter is reset, the drive voltage of the power amplifier 19 is removed and the motor 1 is quickly stopped, also under the influence of the opposing voltage of the tachogenerator 20 supplied through the OR-gate 18. The weft length thus drawn by the motor 1 through the disc 5 from the yarn package 14 and supplied to the weft blowing nozzle 6 is further taken through the weaving shed by this blowing nozzle and by auxiliary blowing nozzles, spaced along the weaving shed width, if provided.

It has been found that the weft transport controlled in this manner may be reproduced with very great accuracy. I

We claim: v

l. A device for intermittently supplying measured weft yarn lengths from a stationary yarn package in a shuttleless weaving machine, comprising a rotatably mounted measuring roller adapted to receive a plurality of windings of yarn drawn from the yarn package, an electric motor of the quick response type having a driving connection with the measuring roller, a control circuit which is connected to supply current to drive the motor and which is intermittently energized to drive the motor during each weft-insertion period of the weaving machine, a yarn brake arranged to brake the yarn on the entrance side of the roller, and a continuously energized tensioning injector which is arranged to exert tension on the leading end of the yarn tangentially of the roller, and which in cooperation with the brake maintains the windings of yarn in constant frictional engagement with the roller.

2. A device according to claim 1, characterized in that the yarn brake comprises an air injector acting in opposition to-the tensioning injector.

3. A device according to claim 1 for a weaving machine in which the weft inserting device comprises an air blowing nozzle, characterized in that this air blowing nozzle is connected in a continuously energized air supply circuit and at the same time constitutes the tensioning injector.

4. A device according to claim 1, comprising a tacho- I'IIOtOI'. 

1. A device for intermittently supplying measured weft yarn lengths from a stationary yarn package in a shuttleless weaving machine, comprising a rotatably mounted measuring roller adapted to receive a plurality of windings of yarn drawn from the yarn package, an electric motor of the quick response type having a driving connection with the measuring roller, a control circuit which is connected to supply current to drive the motor and which is intermittently energized to drive the motor during each weftinsertion period of the weaving machine, a yarn brake arranged to brake the yarn on the entrance side of the roller, and a continuously energized tensioning injector which is arranged to exert tension on the leading end of the yarn tangentially of the roller, and which in cooperation with the brake maintains the windings of yarn in constant frictional engagement with the roller.
 2. A device according to claim 1, characterized in that the yarn brake comprises an air injector acting in opposition to the tensioning injector.
 3. A device according to claim 1 for a weaving machine in which the weft inserting device comprises an air blowing nozzle, characterized in that this air blowing nozzle is connected in a continuously energized air supply circuit and at the same time constitutes the tensioning injector.
 4. A device according to claim 1, comprising a tachogenerator driven by the electric motor, an integrator which the output of the tachogenerator is supplied, and which produces an integrated output signal proportional to the number of revolutions made by the motor shaft, and a circuit which compares such integrated output signal with a preset signal proportional to the desired thread length, and produces a control signal as soon as such integrated output signal equals the preset signal, And a motor control device which is actuated by such control signal and which when actuated stops the motor. 